Low-temperature Vapor Research Articles

RESIDUAL BINDER OF ROAD BITUMINOUS EMULSIONS INVESTIGATED USING THE SUPERPAVE SYSTEM. REVIEW

The article reviews the features of the study of residual binder obtained from bituminous emulsions using the SUPERPAVE system. The need to add improving additives to bituminous emulsions, namely modifiers (polymeric and adhesive additives) and special additives of different effects (solvents, stabilizers, thickeners, defoamers) is characterized. It is determined that the effect of special additives with different effects on the properties of the residual binder of the emulsion is not fully investigated. It is shown that the method of obtaining residual binder from bitumen emulsions in the laboratory is especially important. Today, all methods of obtaining residual binder from an emulsion can be divided into high-temperature distillation methods and low-temperature evaporation. The literature review confirmed that the high-temperature and low-temperature performance characteristics of the residual binder of emulsions primarily depend on the amount and type of modifier and emulsifier used.

Performance improvement and multi-objective optimization of a two-stage and dual-temperature ejector auto-cascade refrigeration cycle driven by the waste heat

This paper presents a two-stage and dual-temperature ejector auto-cascade refrigeration cycle (TEARC) driven by the waste hot water and low-pressure exhaust steam in chemical plants. In this cycle, a throttle valve is provided between the condenser outlet and separator inlet to regulate the composition and mass flow ratio of mixture refrigerant in the two evaporators. The specific enthalpies of refrigerant at the low-temperature (LT) evaporator and medium-temperature (MT) evaporator inlet are respectively reduced via the evaporative condenser and separator, leading to an enhancement in cooling capacity. Energy, exergy, and economic (3E) analyses are conducted to compare the performance between the TEARC and the basic two-stage and dual-temperature ejector refrigeration cycle (BTERC). At the basic operating condition, the TEARC has enhancements of 9.13 % and 9.95 % in COP and exergy efficiency than those of the BTERC. According to the multi-objective optimization results, it indicates that the TEARC's COP, exergy efficiency, and levelized cost of cooling are respectively improved by 8.93 % and 5.67 % and reduced by 1.22 % compared to the BTERC at optimum operating conditions. The simulation results of the proposed cycle reveal a significant performance improvement and the potential for application in waste heat-driven refrigeration.

Decreasing Electrical Resistivity of Ag Film by Low-Temperature Evaporation and Sintering through Azeotrope Application

In the temperature-sensitive components, such as perovskite solar cells, large-area electrical connections with high electrical conductivity are also required. To fulfill the requirements, low-temperature evaporation was realized by preparing binder-free pastes with Ag flakes and a solvent mixture, followed by sintering at 140 °C. The mixed solvent was based on viscous α-terpineol with the addition of an appropriate amount of dipropylene glycol methyl ether acetate or diethylene glycol diethyl ether to achieve an azeotrope composition, followed by the addition of a low-molecular-weight hydroxypropyl cellulose to increase the viscosity and thixotropy. During sintering at 140 °C in air for up to 30 min, the paste with 49.5 wt% α-terpineol, 49.5 wt% dipropylene glycol monomethyl ether acetate, and 1 wt% hydroxypropyl cellulose mixture exhibited an excellent electrical conductivity of 7.72 × 10−6 Ω·cm despite the implementation of low-temperature sintering. The excellent processability of the prepared Ag-based pastes at 140 °C demonstrated their potential for novel application areas.

Heavy metal migration and enrichment in desulfurization wastewater during low-temperature triple effect evaporation process

Zero discharge of desulfurization wastewater from coal-fired power plants has become important. Desulfurization wastewater and gypsum from different stages of the low-temperature triple-effect evaporation process of a coal-fired power plant were collected and investigated. The results showed that after low-temperature triple-effect evaporation, the concentrations of Na+, Mg2+, K+, and Cl− in the desulfurization wastewater increased by 7.91, 7.15, 8.49, and 8.35 times, respectively. With the progress of low-temperature triple effect evaporation process, the concentrations of As, Cd, Co, Cr, Cu, Mn, Se, and Zn in the wastewater after the triple effects were 5.85, 75.44, 1.28, 2.34, 13.66, 5.58, 8.59, and 4.35 times higher than those in the raw wastewater. Mn and Se exceeded the emission limits by 40 and 10 times, respectively. After triple-effect evaporation, the concentrations of As, Cd, Co, Cr, Cu, Pb, Se, and Zn in gypsum decreased to 46%, 26%, 66%, 41%, 35%, 97%, 39%, and 51% of the raw gypsum, respectively. Compared with that of other metal sulfates, the solubility of PbSO4 was extremely low under low-temperature conditions, and some PbSO4 precipitated during the triple-effect evaporation process, leading to a gradual decrease in the Pb concentration in the liquid phase. The mercury compounds in gypsum after the first and second effects were the same as those in raw gypsum, both of which were HgS and HgO. After third effect, the mercury compound in gypsum also included HgSO4. In addition, owing to the promoting effect of the pH of desulfurization wastewater approaching 5.50 on the generation of HgS, the proportion of HgS gradually increased, and the proportion of HgO gradually decreased from the raw gypsum to the third effect gypsum. Therefore, the stability of the mercury compounds in gypsum was enhanced. It can provide a good reference for the migration and enrichment of heavy metals in the low-temperature triple-effect evaporation process, which is beneficial for the clean production and efficient utilization of coal.

Thermodynamic analysis of a modified two-stage transcritical CO2 refrigeration cycle with an ejector and a subcooler

In the application scope of large-scale supermarkets, the practicality of transcritical CO2 refrigeration device has been confirmed to be quite satisfying. A modified two-stage transcritical CO2 refrigeration cycle with an ejector and a subcooler (MTC) is proposed in this paper. In the modified cycle, the ejector recovers expansion works and reduces irreversible losses in the throttling process. The subcooler provides subcooling degree for the CO2 entering the low-temperature (LT) evaporator, thus increasing the refrigeration capacity and improving the COP of the modified cycle. Thermodynamic analysis has shown that the exergy efficiency (ηex) and COP of MTC under given operating condition has been enhanced by 13.7 % and 14.2 % compared to BTC. The discharge temperature at the outlet of high-pressure compressor in MTC is decreased by 8.3℃. Under typical operating condition, the optimal discharge pressure of MTC is 9.07 MPa, which is lower than that of BTC. The correlation to calculate optimal discharge pressure for single-stage CO2 refrigeration cycle is also suitable for MTC under given operating conditions. The MTC has also shown better performance under variable operating conditions. For MTC, when the temperature at the outlet of gas cooler increases from 35 – 45℃, the COP and ηex are enhanced by 14.1 % - 16.1 % and 12.8 % - 14.2 % compared to BTC, respectively. When gas cooler outlet pressure decreases from 11.0 to 7.5 MPa, the COP and ηex are enhanced by 14.0 % - 22.8 % and 13.4 % - 18.7 %. As the evaporating temperature at the cold side of subcooler increases from -25 to -15℃, the COP and ηex increase from 1.82 to 1.98 and 27.4 % to 29.7 %. With the ratio of refrigeration capacity (Rec) between medium-temperature evaporator and low-temperature evaporator varies from 0.7 to 1.2, the COP and ηex are improved by 10.7 % - 16.3 % and 10.7 % - 15.4 % compared to BTC. There is the maximum exergy loss at gas cooler in the MTC, whereas that of BTC is located in the expansion valve before LT evaporator. The economic analysis shows the cost per unit of exergy of MTC is decreased by 11.5 % under typical operation condition. According to simulation results, the modified cycle has better performance in severe working conditions such as high gas cooler outlet temperature and low gas cooler outlet pressure in the given range of working conditions compared to BTC.

Experimental research on chemisorption energy storage performance for industrial waste heat recovery and conversion

This study investigates a solid chemisorption energy storage system utilizing a multi-component chloride salt composite adsorbent with a mass ratio of NH4Cl, CaCl2, MnCl2, and expanded natural graphite treated with sulfuric acid (ENG-TSA). The system features a shell-and-tube heat exchanger and analyzes refrigeration and heat storage performance under varying industrial low-temperature waste heat (60–110 °C) conditions, with condensation and evaporation temperatures of 0–25 °C and discharging temperatures of 40–60 °C. The results indicate that the multi-salt composite adsorbent reduces hysteresis between adsorption and desorption stages. The highest coefficient of performance (COP) and specific cooling power (SCP) were 0.461 and 328 W/kg, respectively, at an evaporation temperature of 25 °C and a charging temperature of 110 °C. Excessively long cycle times negatively affect system efficiency, with optimal performance achieved at a 40-min cycle. The findings highlight the system's effectiveness for industrial low-grade waste heat recovery, providing a solid foundation for future reactor design and material selection.

Treatment of aircraft maintenance wastewater by coupling low-temperature evaporation with Fe–C micro-electrolysis-configured ozonation

ABSTRACT A novel approach combining low-temperature evaporation with Fe–C micro-electrolytic ozone oxidation has been devised for treating substantial volumes of high-concentration organic cleaning wastewater generated during aircraft maintenance activities. The findings from experiments demonstrate impressive average removal rates for various contaminants, including chemical oxygen demand (93.1%), oil concentration (94.0%), suspended solids (98.9%), turbidity (98.8%), chroma (93.8%), total nitrogen (93.7%), and total phosphorus (99.2%). Within this integrated system, the synergistic effects between ozone oxidation, catalytic fillers, and electrochemical processes significantly enhance pollutant removal efficiency. The chemical oxygen demand reduction rates of the cleaning wastewater derived from engine maintenance, mechanical and electrical maintenance, aircraft accessory maintenance, and mixed wastewater exceed 98%. The optimal reaction times for four types of wastewater are 150, 120, 90, and 120 min, respectively. The time can be adjusted according to the different treatment objects in actual operation projects. Moreover, the average concentration efficiency achieved surpasses 92% while meeting all effluent quality standards set forth by municipal sewage networks, and it has reduced the disposal cost of the enterprise by about 80%. This technology provides enterprises with an effective way to reduce energy consumption and expenses.

Mitigating ZrCr2 formation at the Cr/Zr interface through trace doping of Zn, Mg and Sn into Cr coatings: A combined first-principles computational and experimental investigation

This study investigates the suppression of ZrCr2 formation at the Cr/Zr interface by introducing trace amounts of Mg, Zn, and Sn into Cr coatings. Combining the first-principles calculation and experimental analyses, the inhibitory effects of these dopants on ZrCr2 are examined. First-principles calculations predicted that Zn, Mg, and Sn can elevate the formation energy of ZrCr2, with Mg exhibiting the most significant effect, thereby exerting an inhibitory influence on ZrCr2 formation. Experimental findings demonstrate that Sn notably inhibits ZrCr2 formation, resulting in a reduction of ZrCr2 approximately 10%. However, Zn and Mg do not exhibit a substantial inhibitory effect on ZrCr2 due to their low yield resulting from the low vaporization temperature. These results from computational simulations, alongside experimental validations, underscore promising strategies for mitigating ZrCr2 formation, offering valuable insights for enhancing performance in nuclear fuel cladding applications.

Energy and exergy analysis of a novel two-stage ejector refrigeration cycle using binary zeotropic mixtures

To improve the ejector refrigeration cycle performance, this paper presents a theoretical thermodynamic analysis of a novel two-stage ejector refrigeration cycle (TSERC) with a gas-liquid separator using R134a/R32 and R600a/R290 as refrigerant. By separating the relatively low-boiling-point and high-boiling-point refrigerants, the cycle compression ratio decreases, the cycle performance increases, and the energy utilization efficiency can be improved. Energy and exergy analysis were conducted for the traditional single-stage ejector refrigeration cycle (SSERC) and TSERC. The effect of the mixture mass fraction on cycle performance under a fixed external heat source operating condition was studied, and the cycle performance comparisons between TSERC and SSERC at different evaporation temperature, condensation temperature and generation temperature were conducted. Results show that for TSERC, the maximum COP values 0.126 and 0.11, the maximum exergy efficiency 4.51 % and 4 % are obtained as the low-boiling-point mass fraction equals 0.6 and 0.4 respectively for R134a/R32 and R600a/R290. It is found that exergy destruction mainly occurs in the low-pressure sub-cycle of TSERC, the top three largest exergy destruction components are ejector 1, condenser 1 and generator 1, while the smallest exergy destruction occurs in pump 2. In addition, cycle performance comparison between SSERC and TSERC shows that the maximum COP improvement increased by 41.6 % and 89.6 % for 134a/R32 and R600a/R290 for TSERC, while the maximum entrainment ratio improvement increased by 32.4 % and 87.6 %. Moreover, it is concluded that the cycle performance improvement of TSERC is more significant at lower evaporation temperature, higher condensation temperature, and lower generation temperature compared to SSERC.

Study on the effect of volatile organic compounds on the treatment of high-salt wastewater by low-temperature evaporation

ABSTRACT High-salinity wastewater, owing to its intricate composition and challenging treatment requirements, poses a significant hurdle in water environmental governance. In this study, low-temperature evaporation technology is used to tackle wastewater containing the volatile organic compound such as N,N-dimethylacetamide (DMAC). Utilisation of comprehensive approaches involving experimental testing, mathematical modelling, and Aspen Plus software simulations, The influence of DMAC on evaporation efficiency is researched through the following factors which encompassing its effects on boiling point elevation, partial molar activation energy, and the formation of by-products. Additionally, the comparation of the impact of temperature, ionic strength, intermolecular interactions on the evaporation rate and the concentration of the volatile component DMAC in the condensate is also conducted in this study. After conducting a multiple linear regression analysis of evaporation efficiency using the Statistical Product and Service Solutions (SPSS) tool, it was discovered that temperature serves as the primary determinant influencing the evaporation rate. Additionally, ionic strength impacts solution viscosity, intermolecular interactions, and saturated vapour pressure by altering the intermolecular forces, thereby indirectly influencing both the evaporation rate and the quality of condensate water. The comparative analysis of single-effect and double-effect evaporation indicates that the optimal operating condition for double-effect evaporation yields an evaporation rate of 70%, with a remarkable 88% reduction in steam consumption compared to single one. Based on heat and mass balance principles, the mathematical model for double-effect evaporation is established to offer crucial data support for practical industrial applications.

Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) Self-Reinforced Composites via Solvent-Induced Interfiber Welding of Nanofibers.

In this study, we explore an approach to enhance the mechanical performance of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by utilizing the self-reinforcing effect of β-phase-induced PHBV electrospun nanofiber mats. This involves electrospinning combined with low-temperature postspun vapor solvent interfiber welding. Scanning electron microscopy imaging confirmed fiber alignment, while XRD diffraction revealed the presence of both α and β crystalline phases under optimized electrospinning conditions. The resulting composite exhibited significant improvements in mechanical properties attributed to the formation of more perfectly structured α and β polymorphs and enhanced interfacial adhesion of electrospun nanofibers after vapor solvent treatment. This approach offers entirely recyclable and biodegradable materials, presenting the potential for a new family of sustainable bioplastics.

Enhancing Stability of SAPO-37 Molecular Sieve through Aluminum Phosphate Utilization: Synthesis, Stability Mechanism, and Catalytic Performance.

SAPO-37 molecular sieve, characterized by its three-dimensional 12-membered-ring FAU structure, has drawn wide attention due to its unique properties and catalytic potential. However, its susceptibility to framework collapse under low-temperature and humid conditions hinders practical applications, affecting both the reaction performance and sample storage. To tackle this, we utilized aluminum phosphate as a precursor for synthesizing SAPO-37, aiming to modify Si incorporation mechanisms and improve P and Al environments. Solid NMR spectroscopy combined with other techniques proves that the resulting SAPO-37-AP has enriched silicon islands, leading to reduced water adsorption, more reversible structural change, and significantly enhanced stability after low-temperature vapor treatment compared to conventional SAPO-37. Remarkably, SAPO-37-AP, after water vapor treatment, still exhibits superior performance in the liquid-phase Beckmann rearrangement reaction. This approach enhances stability, reduces templating agent amounts, and improves the solid product yield, offering promising practical applications.

Study on heavy metal leaching from steel slag in coastal soft soil and its environmental impact

ABSTRACT To explore the environmental impact of steel slag deposited within a coastal soft soil foundation, the steel slag produced by a steel plant in Fangchenggang city was chosen as a case study. Seawater was collected from the coastal foundation, and water with different levels of salinity was obtained by low-temperature evaporation, filtration, sterilisation, and dilution. Leaching tests of steel slag in artificial seawater with different levels of salinity were carried out according to the Toxicity Characteristic Leaching Procedure (TCLP). The results showed that with the increase in the leaching time and salinity of the solution, the concentration of heavy metals in solution displayed an upward trend; however, the rate of increase decreased once the concentration reached a certain level. From an environmental perspective, it is not advisable to use steel slag as a filler near drinking water, and steel slag should not be used as a foundation material in the high-salinity coastal soft soil layer.

Lattice-Disordered High-Entropy Alloy Engineered by Thermal Dezincification for Improved Catalytic Hydrogen Evolution Reaction.

A disordered crystal structure is an asymmetrical atomic lattice resulting from the missing atoms (vacancies) or the lattice misarrangement in a solid-state material. It has been widely proven to improve the electrocatalytic hydrogen evolution reaction (HER) process. In the present work, due to the special physical properties (the low evaporation temperature of below 900 °C), Zn is utilized as a sacrificial component to create senary PtIrNiCoFeZn high-entropy alloy (HEA) with highly disordered lattices. The structure of the lattice-disordered PtIrNiCoFeZn HEA is characterized by the thermal diffusion scattering (TDS) in transmission electron microscope. Density functional theory calculations reveal that lattice disorder not only accelerates both the Volmer step and Tafel step during the HER process but also optimizes the intensity and distribution of projected density of states near the Fermi energy after the H2O and H adsorption. Anomalously high alkaline HER activity and stability are proven by experimental measurements. This work introduces a novel approach to preparing irregular lattices offering highly efficient HEA and a TDS characterization method to reveal the disordered lattice in materials. It provides a new route toward exploring and developing the catalytic activities of materials with asymmetrically disordered lattices.

Recycling leachate nanofiltration concentrate and preparing a novel and low-cost absorbent dried gel by graft polymerization

Leachate nanofiltration concentrate (LNC), characterized by its complex composition and recalcitrant contaminants, poses a significant environmental challenge. This study explores the synthesis of absorbent gels via free radical polymerization, utilizing LNC as the solvent. Employing urea as the modified material, acrylic acid (AA) as the monomer, N, N′-Methylenebisacrylamide (MBA) as the cross-linking agent, and potassium persulfate (KPS) as the initiator, the resulting gel is stable below 180 °C. It demonstrates an impressive absorbency (Q) exceeding 14.50 g/g with key gel synthesis conditions optimized via response surface methodology (RSM). Subsequent application of the prepared LNC gel in LNC treatment via low-temperature evaporation achieves remarkable pollutant removal, meeting relevant water quality standards. This gel-based LNC treatment method achieves notable reductions in carbon emission and cost to 39.2 kgCO2/kgCOD and 3.4 $/kgCOD, respectively. This study provides a cost-effective and environment-friendly approach for LNC reutilization, and exemplifies the concept of utilizing waste to treat waste, thereby mitigating environmental impact of LNC and advancing gel technology in environmental remediation.

Research on the application of WO3 gas sensor based on noble metals modification in cable fire detection

In the monitoring of cable fire, it is of great significance to be able to conduct early fire warning, which requires that sensors have high sensitivity to the cable vapors at low temperatures. In this study, WO3 thick films modified with Au, Pd, and Pt single or bimetallic nanoparticles were fabricated via magnetron sputtering. Gas sensors utilizing these materials exhibited significant response to the low-temperature vapor emitted by YJV22 and YJY23 cables. Among them, Pd/WO3-20 demonstrated a response value of 20 to the vapor of 81[Formula: see text]C YJV22 cables, marking a remarkable 6.3-fold increase compared to pure WO3, and the response time was 13 s. Similarly, Pt/WO3-10 exhibited a response value of 11.11 to the vapor of 104[Formula: see text]C YJY23 cables, representing a 6.9-fold enhancement over pure WO3 with a response time of 12 s. The heating temperature of cables remains below their critical threshold, indicating that it is in the early stages of cable fires, the findings hold significant implications for early warning systems designed to detect cable fires promptly.

Insight of transport properties of glassy solid electrolytes for energy storage applications

The goal of developing battery systems has attracted researchers' attention for about 30 years, almost since the development of primary electrochemical systems with a lithium anode. To realize the benefits of lithium ion batteries (LIBs) and lithium metal anode batteries, several important issues need to be addressed. The use of liquid non-aqueous electrolytes based on aprotic solvents in lithium battery systems certainly offers advantages over traditional battery systems. However, due to the relatively low evaporation temperatures and high flammability of solvents, liquid electrolytes significantly limit the operating range of battery systems in the high-temperature range. Special measures are required to ensure the safe operation of a lithium-ion battery system. The use of inorganic solid electrolytes (SEs) is one of the most promising directions for improving lithium-ion and solid-state battery systems. The use of SEs will enable the safe cycling of battery systems with both lithium electrodes and intercalation anodes, significantly extend the temperature range of battery operation towards high temperatures and enable the creation of battery systems of new sizes and designs. The development of new solid oxide salt materials and technologies to produce battery systems with electrolytes based on them is an urgent task to solve the above problems.

An Ultralight Capillary-Driven Heat Pipe.

Capillary-driven heat pipes are an effective thermal solution for compacting electronic cooling systems. We advance such a heat pipe thermal solution with ultralightweighting for mobile applications. In our advancement, the envelope that encapsulates the phase-change process of a working fluid is fabricated via electroless plating being ∼40 μm thick. Furthermore, the wick structure that transports condensate to a heat source via capillarity is also electroless-plated onto the envelope's inner surfaces, creating a 100-μm-thick, microporous layer. This wick structure is sequentially superhydrophilized by blackening that forms a nanotexture on the microporous wick layer. An effective density of our prototype ultralight heat pipes (uHPs), as a measure of lightweighting, indicates, on average, a remarkable 73% weight reduction of commercial counterparts with sintered copper powder wick in similar exterior dimensions (e.g., ∼2.7 g, compared to ∼10.0 g) while providing equivalent heat spreading. Furthermore, the uHP operates at a 25% lower evaporator temperature, due to additional heat rejection to the surroundings through the ultrathin-walled envelope and wick.

Thermal analysis of solar energy based organic Rankine cycle cascaded with vapor compression refrigeration cycle

The air conditioning and refrigeration applications use a significant portion of the electrical energy. This research analyses a performance of refrigeration system, which comprises on different configurations of solar based organic Rankine cycle (ORC) and vapor compression refrigeration (VCR) cycles requiring low evaporation temperatures. In this research, the dry natural hydrocarbons such as n-Decane, n-Dodecane and Toluene have been chosen to serve as the working fluids in ORC. Whereas in VCR cycle natural hydrocarbons such as Ethane, Propane, isobutane, isopentane and isohexane have been used because traditional working fluids have a negative environmental impact due to high values of ozone depletion and global warming potential. The simulated results showed that the facility can be operated efficiently with the use solar thermal energy resources within the temperature range 90 to 315ºC and decreasing the need for conventional fossil fuel resources. It was also revealed that the highest efficiency was achieved by n-Dodecane in regenerative ORC, which is 35.34 % at the evaporation temperature of 315ºC and the highest overall coefficient of performance (COPoverall) in regenerative ORCCRS facility was achieved by n-Dodecane in ORC and isopentane in refrigeration cycle which is 1.017 while in case of Simple ORC–VCR facility the highest COPoverall was achieved by Toluene in ORC and isopentane in refrigeration cycle, which is 0.7174 at the evaporation temperature 315ºC.

Analysis of a refrigeration system using carbon nanotubes (CNTs) lubricant and a combination of R290/R600 refrigerants

A combination of R290/R600 refrigerants with low global warming and zero ozone-depleting potential refrigerant was tested with a based lubricant and CNTs nanolubricant in a refrigeration system to improve its performance efficiency and minimise the environmental impact of refrigerants and energy demand by refrigeration systems. CNTs-nanolubricant, an alternative lubricant for the refrigeration system, was made by dispersing CNTs in the based lubricant. By connecting measuring devices at each system component, temperatures and pressures were determined. The experiment’s measured outputs were used to determine the system’s performance. When compared to a 290/600 in the based lubricant, CNTs nanolubricant showed a reduction in work input ranging from 39.8%, a shorter pulldown time, a lower evaporator temperature, an increased coefficient of performance (COP), and a higher cooling capacity of 9.1%. Therefore, the lubricant made of carbon nanotubes (CNTs) presents a viable substitute for based lubricant in a vapour compression system.